So what is this really about? MIUI system is a "dual-boot" system comprising of System One and Two. Updates will go to one of this partition and if you face any issue, you can choose to boot from the other system. This is a security feature. The disadvantage of this is that we get lesser space in the System One partition. In the case of Mi 3/4, there are many developers sharing their custom roms with users and in some cases, the System partition was too small to flash the Google Apps (gapps in short), thus people resorted to resize System One.

Is this necessary for Mi Pad? At this moment, there are not many custom roms available, and I have not come across the situation above. Nonetheless, our fellow MIUI user @coolhunksamii approached me to help make this a reality. So out of curiosity, and to learn, I decided to try it and I had succeeded.

Warnings:
1. If you don't understand the purpose of this, don't try.
2. If you try this, it is at your own risk of breaking your Xiaomi Mi Pad or successfully having a bigger size System One.

Credits:
1. arif920629 of XDA for starting the thread above
2. audahadi of XDA for the zip to enlarge System One for Mi 3/4
3. ElPerroVerde of XDA for the zip of returning System One and Two for Mi 3/4 to stock MIUI partition size
4. The creators of the CWM and TWRP recoveries that I had used

Steps to extend System One to 1.2GB:1. Download Repartition_MI_Pad_1_2GB_zardMi3.zip and Repartition_Stock-Partition_MI_Pad_zardMi3.zip
2. Copy to your Mi Pad3. Change the Mi Recovery to either CWM or TWRP Recovery (I used TWRP)4. Do a backup of your ROM in System One using either CWM or TWRP Recovery (I used TWRP)5. Wipe Cache, Data, System and Dalvik Cache6. Flash Repartition_MI_Pad_1_2GB_zardMi3.zip7. Restore your ROM from point (4) to System One8. Reboot to System and enjoy9. You can confirm the System One size using DiskInfo, System Partitions or Titanium Backup from Google PlayStore (total size is 1.21GB and free size is 688MB).

Steps to reduce System One back to stock MIUI size:1. Do a backup of your ROM in System One using either CWM or TWRP Recovery (I used TWRP)2. Wipe Cache, Data, System and Dalvik Cache3. Flash Repartition_Stock-Partition_MI_Pad_zardMi3.zip4. Restore your ROM from point (1) to System One5. Reboot to System6. You can confirm the System One size using DiskInfo, System Partitions or Titanium Backup from Google PlayStore (total size is 622MB, free size is 75MB)

people who are using cwm recovery and getting bootloop
Long press powerbutton and wait for screen to turnoff
immediately press volume up button and w8 untill mi logo shows up
leave volume up button now,
You will be in cwm recovery
now go to
system 1
> advanced
select boot from system 1
then follow the same method
to make partition